setting the template as the main landing page

Hello,   I am using LaVente template on my wordpress site. However I can't see my main landing page in page list in wordpress.   I have a hunch that this is what causes it to show up poorly in search even though i have SEO set up. Tried everything I found on Google etc. but I can't set this page as a landing page if I don't have to option to select this page because it's not a page so I cant choose it. Because is most probably set as default post or comment idk...   Would much appreciate your help how to set your theme template as a main landing page. web: https://taxigoo.cz/   Thanks a lot and best regrads Taxigoo Team